The long term objective of the project is a complete description of how the two and three-dimensional structure of objects or the environment can be obtained from visual motion in human subjects. The awake behaving monkey is used as a model for such visual processing. Previous studies (Siegel and Andersen, 1988) indicate both species have similar motion psychophysics using highly controlled stimuli consisting of large numbers of moving dots validating the use of the non-human primate as a model for human subjects. Electrophysiological recordings in the awake behaving monkey will be used to explore higher level motion processing. Single neurons will be recorded while the monkey is performing the earlier published psychophysical tasks. The recording study will first phenomenologically describe the properties of neurons in the cortical visual areas of the inferior parietal lobule and "anatomically near" cortex when presented with the structure from motion stimulus. The receptive field structures of these neurons will be examined in order to determine if the response may be explained by local receptive field mechanisms. A comparison will be made between the response of the neurons to the random dot stimuli and to the movement of bars which have the same underlying motion transformation. Finally, the interactions between the motion stimulus and the position of the eye in the orbit will be explored in an attempt to understand how motion is used in the perception of surrounding space. This study is related to the mental health of individuals in that it seeks to understand how is of incoming visual stimuli is performed by the inferior parietal lobule. The understanding of such mechanisms is necessary in understanding the damage that occurs following stroke and other cerebral compromise.